The present invention relates to truss-like fabricated joists or beams made of wood chords and, more particularly, to an improved corrugated staple or metal fastener for joining together the wood chords to form a joist or beam.
In the construction of houses and other relatively small buildings, it is conventional to use solid wood beams for floor joists, ceiling supports, roof joists and the like. Generally such beams have nominal cross-sectional dimensions of 2.times.6, 4.times.8, 4.times.10, 4.times.12, etc., (inches). However, the increased demand and decreasing availability of high grade lumber has resulted in an increase in the price of lumber necessary for making such beams. The present invention relates to fabricating beams made of more readily available, less expensive, smaller cross-section lumber such as 2.times.4 which lumber may be interconnected with metal struts and where the wood members at the ends of the beam are interconnected with improved corrugated staples or fasteners.
Thus, in accomplishing the fabricated beam construction disclosed herein, it is contemplated to use additional wood strips interposed between the wood chords for absorbing shear load. The use of wood pieces between chords of a truss is known and illustrated, for example, in U.S. Pat. No. 3,748,809 issued July 31, 1973 and in Swiss Pat. No. 306,573 issued Apr. 30, 1955. However, the shear force absorption and resistance to bending is very limited in the constructions disclosed in those prior patents.
It is also known to utilize corrugated staples or fasteners to interconnect adjacent wood members in truss constructions as illustrated for example, in Australian Pat. No. 247,162 published Jan. 26, 1961.
Prior to the present invention, however, the corrugations of metal staples were oriented in a single direction or oriented in two directions at an acute angle relative to each other, and did not strive for fiber end loading as a result of horizontal shear. The prior staples, however, provided limited resistance to pulling out of the wood and limited resistance to bending when the beam was subjected to loading.